1. Field of the Invention
The present invention relates generally to improvements in a yagi antenna, and more particularly pertain to new and improved adjustable antenna elements wherein the length of each antenna element rod is telescopicly adjustable in length from a collapsible position to an operating length for a predetermined frequency of operation. The spacing between the director element and reflector element is slidably adjustable on the antenna boom for independent spacing with respect to the half-wave active dipole element. The antenna boom has two mast support holes for mounting the antenna for either horizontal or vertical polarization.
2. Description of the Prior Art
In the field of yagi antennas, it has been the general practice to employ antennas with mechanically fixed antenna elements, nonadjustable element rods, mechanically fixed element spacing, and a single mast mounting hole. Such an antenna has been unsatisfactory in that the center frequency and polarization of the antenna is mechanically fixed when the antenna is mounted for installation. Adjustment of either the center frequency of the antenna and/or the polarization is impracticable if at all possible. This is due to the mechanical mounting of the elements onto the antenna boom and the securing of the antenna boom to the supporting mast. The antenna when assembled and mounted, has usually been manufactured and cut to a center frequency, and is not shiftable from that frequency as the elements are a fixed length. Further, the antenna elements are not removable from the antenna boom for the purposes of storage or transporting the antenna from one location to another. The prior art is illustrated by the U.S. Pat. issued to Wentworth, No. 2,673,295, which shows a foldable two element in FIG. 1 that is used for over a limited frequency range.